So you're minding your own business running your colony, when you suddenly get an error message or see bizarre behaviour like patients not getting off MedPods, machine gun turrets not firing at targets, or lolita ratgirls suddenly vomiting uncontrollably after eating Replimat meals.
Running mods in RimWorld is like adding new accessories to a sports car while it is rolling down the highway - the more parts/mods you have, the more complex the interactions between them, and the more likely something will go wrong.
To complicate matters, most parts/mods are made by different authors, who cannot realistically design their mods to work with every other mod or every possible play style.
Finally, many modders have professional careers, families and other real-life commitments. To them, RimWorld is just a hobby, and they often have very little time each day/week/month to decipher gigabytes of log files or chase down transient bugs.